Alpha_s from the Lattice Potential

TL;DR

This paper determines the strong coupling constant alpha_s at short distances in quenched QCD using lattice calculations, finding two-loop asymptotic behaviour and estimating Lambda-parameters and alpha_s at the Z boson mass.

Contribution

It provides a precise lattice-based determination of alpha_s from the static quark potential, including the zero-flavour Lambda-parameter and estimates for full QCD effects.

Findings

Alpha_s exhibits two-loop asymptotic behaviour at low momenta.

Lambda-parameter in quenched QCD is determined as 0.630(38) in units of the string tension.

Estimated alpha_s at the Z boson mass is approximately 0.102 with uncertainties.

Abstract

We present an extensive study on the direct determination of the running coupling alpha_s from the static quark antiquark force at short distances, in quenched QCD. We find from our high statistics potential analysis that alpha_qq exhibits two-loop asymptotic behaviour for momenta as low as .5 GeV. As a result, we determine the zero flavour Lambda-parameter to be Lambda^0_MSBAR = 0.630(38)\sqrt{\sigma} = 293(18)^{+25}_{-63} MeV. A rough estimate of full QCD effects leads to the five flavour value alpha_MSBAR(m_Z) = .102^{+6}_{-11}. A comparison with other lattice results is made.